"I do not have the same role as in the national team, where I have to stay back and control things.
"I like both roles. In the national team I feel great, but here it's a lot of fun to push forward from time to time.
"But I'm not a 10 (behind the striker), I'm still an 'eight', a box-to-box player."
Dortmund are the only team yet to lose in Germany's top flight this year and with Bayern third after defeats to Hertha Berlin and Borussia Moenchengladbach, Witsel sees a great chance for the hosts.
"They have not been good for a few weeks, so it's up to us to take advantage," said Witsel.
"But it's not going to be an easy match. Bayern can wake up for games like this, so it will be up to us to pay attention."
With two thirds of the season still to go, Witsel says no one in the Dortmund squad is yet daring to dream of a first league title since 2012 despite their unbeaten start.
"The goal is to qualify for the Champions League next year, so we are in a favourable position, but no-one in the dressing is talking about winning the championship," he insisted.
A crowd of over 80,000 is expected and Witsel is looking forward to playing Dortmund's biggest league home game of the season in front of Signal Iduna Park's famous 'Yellow Wall' -- the south stand which holds almost 25,000 baying fans.
"This is my first (home game against Bayern) and I can't wait to see how it feels in terms of atmosphere," Witsel said on Thursday.
"Although every time we play at home there is a mad atmosphere, I think against Bayern it will be a little more."